Improvement in botary blowebs



P. H. &--'F. M. ROOTS. ROTARY BLOWER Patented Aug.'11,' 1868.

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P. H. ROOTS AND F. unoors, or CONNL-ERSVILLE INDI'A'NA.

Letters Patent No. 81,009, dated August 1 1, 1 868.

\ IMPROVEMENT IN ROTARY BLOWERS.

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TO .ALLLWHOM IT MAY CONCERN: v I

f Be it known that we, I. H. ROOTS and F. M. Rows, of Conncrsville, inthe county of Fayette, and State .of- Indiana, have invented a new andimproved Rotary Blower; and we do hereby declare that the following is afull',.clear, and exact description thereof, which will enable othersskilled in the art to make and use the same,

reference being bad to the accompanying drawings, forming a part of thisspecification, in which- .r-Figure 1 represents a vertical transversesection of our rotary blower.

Figure 2 is a sectional view of two abutments, showing their relativepositions as they'have hitherto been made, and the source of thedifficulty hitherto experienced.

Similar letters of reference indicate corresponding parts.

This invention relates to a new manner of constructing the abutmcnts inthat class of rotary blowers or engines in which two rcvolving abutmentsare used, whose circular portions or peripheries are formed of arcs ofdifi'erenFdiamefrsQ i invention relates also to constructing theabutments with'shell-pistons, each having one or more arms or wingsextending from the centre cylinder to the outer circular part of thepiston, which is either cast on the armsor otherwise secured to theminthe proper manner, whether made of metal or, wood. Thesearms or wingsextend the entire length of the cylinder, thus forming a sort ofcontinuous cross-head. I

This invention consists, further, in constructing the centre cylinder,of plaster of Paris or'other material. in

a plastic or molten state.

This invention consists, finally, in forming the pistons of suchproportions, by suitably reducing their arcs and increasingcorrespondingly the recesses, as will overcome difiiculties experiencedin former methods of construction. Y

The objcct of this invention is to construct the abutments of rotaryblowers, of sufliciently lightweight to adapt them't'o run at such speedas is necessary to force any considerable volume of air, and at thesometime so to dispose of the metal as to secure adequate strength, andalso to construct them either partly of wood or entirely of metal. I

And, finally, the object of this invention is so to proportion thepistons and recesses as to obviate difiicu'lties ,which have renderedmachines made as described in the Letters Patent granted to us, January21, 1868, (No.

73,654,) almost useless. V

-A B are twocoacting, rotating abutments, mounted on two shafts, G G.Each abutment consists of two pistons, a a, and two interveningrecesses, 11 b, and a centrc cylinder, c c, as shown in fig. 1. Theperipheries of the abutments are formed in the same manner as describedin the Letters Patent above referred to, with exceptions that will benoted.

From two points, 0 C, which are the centres of the shafts, and taken atany desired distanccapart according to the size of the machine to'beconstructed, are described two circles, c c, ofequal radii, each of.which may be about one-fourth the distance the centres C C are apart.These circles may, howevcr,bedcscribed with a radius greater or lessthan thathore stated, and may also be made operative with unequal radii,ifidesirecl. The circles c c constitutethe centre cylinders of theabutments. The radius for forming the pistons is the distance from thecentre of one of these circles c c to the nearest point in theperipherypf the other 'cii'cle. Of thegperipheries of each of thecircles d d" thus formed, two arcs, of'about eighty degrees, are takenon opposite sides of the circle, and the corresponding recess will.consist of gone hundrcd' degrees, whereas in the former patent, both thepiston and the recess consisted each of ninety degrees.

Abutments may also be advantageously made for various purposes, unlikeeach othcra For instance, the

pistons of one abutment may consist of arcs of fifty degrees, instead ofsixty, and its recesses of one hundred aiid thirty degrees, instead ofone hundred and twenty, and the corresponding abutment will require itspistons -to be one hundred and ten degrees, instead of one hundred and,twenty, a.nd its reccssesconsist oilscvcnty instead of sixty'degrees.

s oes 2 The importance of the object gained by thus shortening the arcsof the pistons will' be readily understood by reference to fig. 2, whichrepresents the position of the abutments when the tips of two pistonsare at the I same time in contact with the centre cylinders. Thisposition occurs four times to each revolution of the abutmcnts together.As the pistons approach or reach this position, a violent concussion isproduced by the sudden compression of the air caught in the ellipticalrecess '0, shown in fig. 2, from which recess, for'a brief portion ofthe revolution of the parts, there is no escape for the air. Soviolcntis this concussion, that the noise produced by it with a blower runningat a moderate speed, can be heard a quarter of a mile or more, thusrendering the machine intolerable and inadmissible in a work-shop orfoundry, as conversation would be impossible near the machine. When moredense fluids, as water, are acted upon, the 'ditliculty experienced isstill greater.

A pump made with pistons and recesses of ninety degrees can, under anycircumstances, move only with a jerking and irregular motion, causinggreat strain to the maehine, and attended with great loss of power, andif made strictly accurate and tight, is not an operative machine. It hasbeen by numerous and expensive experiments that the seat of thedifiiculty'has been ascertained and the remedy devised. Whenthe-abutmcnts, in the course of their revolution, come to occupy therelative position shown in fig. 2, a line drawn through the centre ofany one piston to the centre of the opposite piston, forms ananglc'offorty-five degrees with a line drawn from the centre of oneshaft, 0, to the centre of the other shaft, 0. In this'ppsition the tipsof the two pistons are at the same time iii contact with the two centrecylinders, and form'betwccn them an elliptical '--recess, shown at 'u,fi 2. As the oistons a roach this ositio h, the air is violentl comressed, and on reach- &' 1 PP P E P ing this position, there is noescape for the compressed-air, as the tips of the pistons arerespectively iii' icontact with the centre cylinders. In order toobviate this difiiculty, it is found necessary to prevent this doublecontact. By removing a portion of the tips of the pistons, an opening oroutlet is formed for the air, so that when the pistons come into theposition stated above, the tipsof both pistons are disconnected fromtheir respective centre cylinders, until the described position ispassed. Asthe air finds an escape through the openings thus formed, theconcussion'is thus avoided.

- By reducing the arc ofthe piston about ten degrees, nearly allthenoise and concussion of the air is obviated. This reduction can bevaried according to the density of the fluids acted upon, and for densefluids should be increased to fifteen or twenty degrees; It is evident,also, that by reversing the application of the principle, and removing aportion of the centre cylinder, as indicated by the red lines at a: w,an escape may be made for the air caught in the recess 11. But as themotion of the surface of the centre cylinder is so much slower than thatof the pistons, the opening thus formed would not be so instantly closedwhen no longer needed to be opened, yet the object is well accomplishedby this arrangement.

I The construction of the shell-pistons and centre cylinders is clearlyshown in fig. 1. .In the abutment A, one piston is constructed with onearm or wing, c, extending from the centre cylinder to the outer circle,a, of the piston with which it is cast. The other piston has two arms,to which the outer circular part of the piston a is cast. The centrecylinder, c, is made of plaster of Paris, or other plastic or moltenmaterial, and is held in position by suitable projections, We usuallycast the plaster of Paris in a mould to its exact dimensions. Any cheapmetal, as zinc, could be substituted and cast in like manner.

In the abutment B, each piston has one arm, with suitable projections orflanges, n 12., at their extremity,to which wood or suitable material isfastened by belts or screws, to form the external circular parts of thepistons. The centre cylinder is formed of wood, fastened with screws orbolts.

, We are thus enabled to construct the abutments of sutiiciently lightweight toadapt' them for the purpose of blowers, and at the same time,with accuracy and all necessary strength. These abutments are made toco-operate together by two equal-sized cog-whecls.

In fig. 2, we show a cross-section of the abutrnents of a blower,substantially as they have been hitherto constructed.

The air confined in the elliptical space, and having no means of escapefor a certain length of time, is the cause of the difiic'ultyexperienced, and which 'is inseparable from blowers or pumps constructedwith pistons whose arcs are ninety degrees. It is true that we can in ameasure overcome the difficulty, and give relief by cutting grooves thelength of the interior cylinders, as shown in a: x, fig. 2, but weprefer to reduce the arc of the piston as described above.

Having described our invention, we claim as new, and desire to secure byLetters Patent- 1. The co-operating abutments A B, constructed withskeleton pistons, having their external circular periphcries connectedby'longitudinal arms to the centre cylinders, as and for the purposespecified.

2. The-abutmcnts A B, having their centre cylinders made of plaster ofParis, or other plastic or molten material, substantially as and forfthcpurpose set forth.

3. The abutments A B, having the arcs of their pistons so constructed asto become simultaneously disconnected from their respective centrecylinders at certain portions of their revolutions, as herein described.

I. H. ROOTS, F. M.'ROOTS.

Witnesses ALEX. F. Ronnn'rs, WM. F. McNAMAnA.

